With reference to FIGS. 1 and 2, a number of antenna systems have been proposed which provide for the reception of satellite transmission signals, S (FIG. 2), from a satellite 11, such as transmission signals for satellite digital audio radio service (SDARS), on mobile structures, such as an automotive vehicle, V. SDARS, for example, operates on the S-band frequencies ranging between 2320–2345 MHz. FIG. 1 illustrates a known after-market antenna system 1a that allows transfer of radio frequency (RF) energy across a dielectric, such as glass 3a, for reception of the satellite transmitted signals, S. The antenna system 1a provides for the transfer of RF energy through the glass 3a or other dielectric surfaces to avoid the undesirable procedure of having to drill holes, for example, through the windshield or window of a vehicle, V, for installation. Although adequate for most applications, after-market glass-mount antenna systems have been considered advantageous because they obviate the necessity of having to provide a proper seal around an installation hole or other window opening to protect the interior of the vehicle, V, and its occupants from exposure to external weather conditions.
In the known antenna system 1a depicted in FIG. 1, RF signals from an antenna 2a are conducted across the glass surface 3a via a coupling device 4a that typically employs capacitive coupling, slot coupling or aperture coupling. The portion of the coupling device 4a on the interior of the vehicle, V, is connected to a matching circuit 5a which provides the RF signals to a low noise amplifier (LNA) 7a at the input of a receiver 8a via an RF or coaxial cable 6a. 
FIG. 2 illustrates an alternative embodiment of the antenna system 1a of FIG. 1, except that antenna system 1b in FIG. 2 includes an antenna 2b, which may range in height from approximately 35–80 mm, that has been displaced to the roof of the vehicle, V, and is retained by a magnet or other securing means (not shown). Through cable 3b, the RF signal travels to the coupler 4b, which is mounted exteriorly on the vehicle's glass (e.g., back windshield), and to second coupler 4b, which is mounted on the glass, such that the second coupler 4b is positioned on the interior of the vehicle, V, in a directly opposing relationship to the first coupler 4b mounted on the exterior of the glass. The RF signal then travels through RF cable 5b to LNA 6b and then through RF cable 7b to receiver 8b. Known coupling devices that are similar to the coupler 4b may include other performance enhancements, such as an integrated receiver unit that minimizes cable runs so as to minimize coupler losses.
Both types of antenna mounting systems 1a, 1b illustrated in FIGS. 1 and 2 suffer from various deficiencies. First, the antennas 2a, 2b of FIGS. 1 and 2, respectively, is, in all likelihood, a second or even third antenna positioned on the vehicle (i.e. an additional antenna in view of the original equipment manufacture (OEM)-installed AM/FM antenna), and thus adds an unsightly appearance to the vehicle, V. Regarding the window mount antenna system 1a, RF coupling loss through the glass 3a is generally 1 dB or higher. This causes an increase in noise that results in degradation of receiver sensitivity. Even further, the couplers 4a may obstruct vehicle operator vision while also generally making the appearance of the vehicle, V, unsightly.
The vehicle body mount (i.e. roof mount) antenna system 1b includes other maintenance, safety, and performance issues. For example, the installation of antenna 2b is located remotely with respect to LNA 6b and radio receiver 8b, which is generally considered unattractive to consumers of mobile satellite services, such as SDARS. This is true for several reasons. First, the roof mounted antenna 2b is unsightly, not only to the external observer, but also to the vehicle occupants where the RF cables 5b, 7b must be routed through the interior of the vehicle, V. Secondly, as a result of height restrictions on car carriers, truck carriers, or other vehicle carriers, an antenna 2b placed on the roof has to be below some maximum height, such that the overall vehicle height does not exceed the maximum allowable height whereby this causes a problem with being loaded on a carrier loaded on a carrier.
Thirdly, RF transmissions are often subject to multi-path fading. This is especially true of satellite transmitted signals, S. Signal blockages, or obstructed satellite signals, O (FIG. 2), at the antenna can occur due to physical obstructions between a transmitter (e.g. the orbiting satellite 11) and the receiver (e.g. the antenna 2b on the vehicle, V), which undesirably results in service outages. For example, as illustrated in FIG. 2, the physical obstructions that the antenna 2b typically encounters may be tall buildings, B, or trees, T, that impede line of sight (LOS) of the antenna 2b. In this scenario, SDARS service outages may occur when noise or multi-path signal reflections are sufficiently high with respect to the reception of the desired signal, S.
A need therefore exists for a vehicle antenna system that provides an effective means for reception of satellite transmitted signals while reducing maintenance issues and increasing signal performance. A need also exists for a vehicle antenna system that prevents additional holes from being drilled in a vehicle's exterior shell. Even further, a need also exists for a vehicle antenna system that eliminates the need to position a relatively large, unsightly antenna on the roof of a vehicle. Yet even further, a need also exists for a vehicle antenna system that eliminates the need to locate a magnetically mounted antenna on the roof or glass of a vehicle, or to use antenna couplers on the glass of a vehicle.